Richness of Spiral Magnetic States in Strontium Ferrite Thin Films

Perovskite strontium ferrite, SrFeO₃, hosts a variety of spiral magnetic phases at low temperature including multi-q states of different proper screw and/or cycloid ordering ^[1]. Among them is a phase believed to support topologically-protected magnetic structures and may explain an observed finite-field anomaly in Hall effect ^[2].
SrFeO₃ is a fascinating material because, unusually, these effects exist despite the centrosymmetry of the crystal structure. Instead of a Dzyaloshinskii-Moriya interaction, the helimagnetism has been suggested to arise due to an interplay of electronic interactions ^[3].
We have optimized the growth and stability of epitaxial thin films of SrFeO₃ grown by pulsed laser deposition. Then, using resonant soft x-ray scattering, we study how these complex magnetic orderings depend on the biaxial strain state, which potentially influences the electronic structure.

[1] Ishiwata, S. et al. Versatile helimagnetic phases under magnetic fields in cubic perovskite SrFeO₃, Phys. Rev. B 84, 1–5 (2011).
[2] Ishiwata, S. et al. Emergent topological spin structures in the centrosymmetric cubic perovskite SrFeO₃, Phys. Rev. B 101, 134406 (2020).
[3] Mostovoy, M. Helicoidal ordering in iron perovskites, Phys. Rev. Lett. 94, 137205 (2005).